Electronic systems and equipment such as computer systems, network interfaces, storage systems, and telecommunications equipment are commonly enclosed within a chassis, cabinet or housing for support, physical security, and efficient usage of space. Electronic equipment contained within the enclosure generates a significant amount of heat. Thermal damage may occur to the electronic equipment unless the heat is removed.
Electronic systems commonly include heat-dissipating components such as processors, central processing units (CPUs), signal processors, and others. One or more fans are used to push air through the system and over components to avoid overheating of the heat-dissipating components. In recent years electronic systems have become more densely packaged so that system design within power and heat dissipation allowances has become more difficult. This system evolution creates design challenges in aspects of power consumption and the effect of fans on overall system heat dissipation characteristics.
An electronics system may have multiple fans including, for example, multiple fans arranged in series to supply sufficient cooling and redundancy in case of failure of one or more fans. If one or more of the series-connected fans fails due to any of various mechanical or electrical failures, power failure or shutdown due to attempts to operate above a system power budget, physical obstruction of a fan rotor, or the like, the failed fan may create a drag on cooling airflow through the system. Drag in the airflow pathway can result in increased demand on other fans, overheating of electronic components and devices, and degradation in electronics performance. Electronics cooling fans typically fail when motor bearing lubricant dries, which may result in a locked rotor. Fan failure may create heavy resistance to airflow through the electronics system due to blockage created by stationary fan blades.